It is a risk management thing. What is the probability that humanity figures out a way to cheaply and safely generate enough energy that we can afford to pull global warming gasses out of the air and stop burning fossil fuels? It seems to me that unless you peg that north of 95% you'd want to manage the risk that it doesn't work out.
Bah, you're being too pessimistic. If we don't invent a new, cheap and safe fuel source I'm sure we'll have invented cheap and safe space travel so we don't have to worry about that crap. Then all we have to do is use untried and untested techniques to change the atmosphere on Mars or Venus to make the planets habitable.
Didn't you ever read a sci-fi novel? Geeze, you're such a Buzz Killington :p
